layout/style/nsCSSPseudoElements.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 /* atom list for CSS pseudo-elements */
   8
   9 #include "nsCSSPseudoElements.h"
  10
  11 #include "mozilla/ArrayUtils.h"
  12
  13 #include "nsCSSAnonBoxes.h"
  14 #include "nsDOMString.h"
  15 #include "nsGkAtomConsts.h"
  16 #include "nsStaticAtomUtils.h"
  17
  18 using namespace mozilla;
  19
  20 // Flags data for each of the pseudo-elements.
  21 /* static */ const uint32_t nsCSSPseudoElements::kPseudoElementFlags[] = {
  22 #define CSS_PSEUDO_ELEMENT(name_, value_, flags_) flags_,
  23 #include "nsCSSPseudoElementList.h"
  24 #undef CSS_PSEUDO_ELEMENT
  25 };
  26
  27 /* static */
  28 nsStaticAtom* nsCSSPseudoElements::GetAtomBase() {
  29   return const_cast<nsStaticAtom*>(
  30       nsGkAtoms::GetAtomByIndex(kAtomIndex_PseudoElements));
  31 }
  32
  33 bool nsCSSPseudoElements::IsPseudoElement(nsAtom* aAtom) {
  34   return nsStaticAtomUtils::IsMember(aAtom, GetAtomBase(),
  35                                      kAtomCount_PseudoElements);
  36 }
  37
  38 /* static */
  39 bool nsCSSPseudoElements::IsCSS2PseudoElement(nsAtom* aAtom) {
  40   // We don't implement this using PseudoElementHasFlags because callers
  41   // want to pass things that could be anon boxes.
  42   MOZ_ASSERT(IsPseudoElement(aAtom), "must be pseudo element");
  43   bool result = aAtom == nsCSSPseudoElements::after() ||
  44                 aAtom == nsCSSPseudoElements::before() ||
  45                 aAtom == nsCSSPseudoElements::firstLetter() ||
  46                 aAtom == nsCSSPseudoElements::firstLine();
  47   NS_ASSERTION(
  48       result == PseudoElementHasFlags(
  49                     GetPseudoType(aAtom, EnabledState::IgnoreEnabledState),
  50                     CSS_PSEUDO_ELEMENT_IS_CSS2),
  51       "result doesn't match flags");
  52   return result;
  53 }
  54
  55 /* static */
  56 PseudoStyleType nsCSSPseudoElements::GetPseudoType(nsAtom* aAtom,
  57                                                    EnabledState aEnabledState) {
  58   Maybe<uint32_t> index = nsStaticAtomUtils::Lookup(aAtom, GetAtomBase(),
  59                                                     kAtomCount_PseudoElements);
  60   if (index.isSome()) {
  61     auto type = static_cast<Type>(*index);
  62     return IsEnabled(type, aEnabledState) ? type : Type::NotPseudo;
  63   }
  64
  65   return Type::NotPseudo;
  66 }
  67
  68 /* static */
  69 nsAtom* nsCSSPseudoElements::GetPseudoAtom(Type aType) {
  70   MOZ_ASSERT(PseudoStyle::IsPseudoElement(aType), "Unexpected type");
  71   size_t index = kAtomIndex_PseudoElements + static_cast<size_t>(aType);
  72   return nsGkAtoms::GetAtomByIndex(index);
  73 }
  74
  75 /* static */
  76 already_AddRefed<nsAtom> nsCSSPseudoElements::GetPseudoAtom(
  77     const nsAString& aPseudoElement) {
  78   if (DOMStringIsNull(aPseudoElement) || aPseudoElement.IsEmpty() ||
  79       aPseudoElement.First() != char16_t(':')) {
  80     return nullptr;
  81   }
  82
  83   // deal with two-colon forms of aPseudoElt
  84   nsAString::const_iterator start, end;
  85   aPseudoElement.BeginReading(start);
  86   aPseudoElement.EndReading(end);
  87   NS_ASSERTION(start != end, "aPseudoElement is not empty!");
  88   ++start;
  89   bool haveTwoColons = true;
  90   if (start == end || *start != char16_t(':')) {
  91     --start;
  92     haveTwoColons = false;
  93   }
  94   RefPtr<nsAtom> pseudo = NS_Atomize(Substring(start, end));
  95   MOZ_ASSERT(pseudo);
  96
  97   // There aren't any non-CSS2 pseudo-elements with a single ':'
  98   if (!haveTwoColons &&
  99       (!IsPseudoElement(pseudo) || !IsCSS2PseudoElement(pseudo))) {
 100     // XXXbz I'd really rather we threw an exception or something, but
 101     // the DOM spec sucks.
 102     return nullptr;
 103   }
 104
 105   return pseudo.forget();
 106 }
 107
 108 /* static */
 109 bool nsCSSPseudoElements::PseudoElementSupportsUserActionState(
 110     const Type aType) {
 111   return PseudoElementHasFlags(aType,
 112                                CSS_PSEUDO_ELEMENT_SUPPORTS_USER_ACTION_STATE);
 113 }
 114
 115 /* static */
 116 nsString nsCSSPseudoElements::PseudoTypeAsString(Type aPseudoType) {
 117   switch (aPseudoType) {
 118     case PseudoStyleType::before:
 119       return u"::before"_ns;
 120     case PseudoStyleType::after:
 121       return u"::after"_ns;
 122     case PseudoStyleType::marker:
 123       return u"::marker"_ns;
 124     default:
 125       MOZ_ASSERT(aPseudoType == PseudoStyleType::NotPseudo,
 126                  "Unexpected pseudo type");
 127       return u""_ns;
 128   }
 129 }
 130
 131 #ifdef DEBUG
 132 /* static */
 133 void nsCSSPseudoElements::AssertAtoms() {
 134   nsStaticAtom* base = GetAtomBase();
 135 #  define CSS_PSEUDO_ELEMENT(name_, value_, flags_)                   \
 136     {                                                                 \
 137       RefPtr<nsAtom> atom = NS_Atomize(value_);                       \
 138       size_t index = static_cast<size_t>(PseudoStyleType::name_);     \
 139       MOZ_ASSERT(atom == nsGkAtoms::PseudoElement_##name_,            \
 140                  "Static atom for " #name_ " has incorrect value");   \
 141       MOZ_ASSERT(atom == &base[index],                                \
 142                  "Static atom for " #name_ " not at expected index"); \
 143     }
 144 #  include "nsCSSPseudoElementList.h"
 145 #  undef CSS_PSEUDO_ELEMENT
 146 }
 147 #endif